JPS6256364A - High strength oxidation-resistant carbon material and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-strength, oxidation-resistant carbon material made of a sintered body of a mixture of a semi-inorganic polymer compound and raw coke powder, and a method for producing the same.

Although carbon materials have many excellent properties such as high temperature strength, thermal shock resistance, high thermal conductivity, good electrical conductivity, and low thermal expansion, they have the disadvantage of being easily oxidized at high temperatures. For example, when a carbon material is heated in the air, it begins to oxidize at around 300°C and rapidly progresses above 600°C. Therefore, although carbon materials have excellent high-temperature properties, their use at high temperatures is limited to non-oxidizing atmospheres and cannot be used in the atmosphere.

In order to improve the defects and α of such carbon materials and improve their oxidation resistance, there are methods of impregnating them with phosphoric acid compounds, methods of impregnating or coating them with film-forming components, and methods of impregnating or coating carbon or graphite with silicon carbide and silicon. Other methods have been proposed, such as adding iron or adding a silicic acid binder mainly composed of silicon carbide and silicic acid. However, the method of impregnating the carbon material with a phosphoric acid compound is a method of raising the oxidation starting temperature of the carbon material by about 100 to 200 degrees Celsius at most, and is not a drastic solution. In addition, the oxidation resistance of the carbon material can be considerably improved by impregnating or coating it with a positive film-forming component, but this depends on the glass film formed on the surface of the carbon material, so it may cause uneven coating, damage to the film, or There is a risk that oxidation may progress locally due to peeling due to the difference in thermal expansion coefficient between the glass film and the glass film, and a stable effect cannot be expected.Additionally, a method of blending silicon carbide or other binders with carbon or graphite Although the oxidation resistance is considerably improved, the effect is still insufficient. For example, heating in air at 900°C for 5 hours causes oxidation I17 loss of 10-30%, and the binder For use, the densification of the sintered image is hindered and its strength is reduced.

Furthermore, as a carbon material with improved oxidation resistance, predetermined amounts of boron carbide powder and silicon carbide powder are added to raw coke powder.
It is known that after sufficient grinding treatment to generate adhesiveness and sinterability, the product is molded and sintered at high temperature in an inert atmosphere (Tokuban Sho No. 56-140075,
JP-A No. 59-131576, JP-A No. 159-213
No. 674).

For the above carbon material, it is necessary to uniformly disperse and mix boron carbide powder and silicon carbide powder in the coke through a grinding process, and for this purpose, the boron carbide and silicon carbide used are required to be fine powders. and requires a longer grinding process. However, uniform dispersion by grinding and mixing powders is difficult. For this reason, satisfactory oxidation resistance has not been obtained in high-temperature, long-term tests. Furthermore, the strength of the above carbon material is obtained by particle reinforcement with boron carbide and silicon carbide, but it is not satisfactory due to insufficient dispersibility. This powder is generally used as a highly hard material or as a wear-resistant material, and has the problem that the container is severely worn during the grinding process, making it difficult to increase productivity. There is.

The present invention solves the problem of easy oxidation of carbon materials under high temperature conditions, and provides an oxidation-resistant carbon material with excellent strength and its s! ! provide a legacy.

The carbon material of the present invention is made of a sintered body of a mixture of a semi-inorganic polymer compound and raw coke powder. The above-mentioned semi-inorganic polymer compound has a temperature of "c700~2" in a non-oxidizing atmosphere.
By heating to 000°C, it is converted into the following ceramic.

A ceramic mainly composed of SiC which is amorphous and is either α-type, β-type, or a mixed phase thereof.

The semi-inorganic polymer compound in the present invention includes the following (a) to
It is characterized by at least 61 types of compounds selected from the group (f).

(,) In the polycarbosilane formula represented by the following formula, R1-
R1 is each independently hydrogen, -1 or less alkyl group,
Haloalkyl group of C4 or less, phenyl group% C5-C6
is a dichlorofurkyl group, a benzyl group or a vinyl group; n is 10 to 1oooo.

(b) In the polycarbosiloxane formula represented by the following formula,
R7-R2 each independently represent hydrogen, an alkyl group of C4 or less, a haloalkyl group of 04 or less, a phenyl group, C5
-C- is a cycloalkyl group, benzyl group or vinyl group; n is 10 to ioooo; and X units and y units (repeat includes either random, block, or both).

(c) A polysiloxane compound represented by the following formula, where:
R+-R3 each independently represents hydrogen, C1 or less alkyl M, C, or less haloalkyl group, phenyl group, C6-
CI, a cycloalkyl group, a verzyl group, or a vinyl group; n is 1 to ioooo; and the repetition of a units and b units includes either or both of random and block.

(d) the polysiloxane compound of the surface top (e) and one or more organic compounds selected from aliphatic polyhydric alcohols, aromatic alcohols, 7 alcohols, or aromatic carboxylic acids; A modified polysiloxane compound obtained by reacting in an atmosphere inert to the reaction at a temperature within the range of 250 to 450°C, optionally in the presence of a catalyst.

(e) At for the polysiloxane compound of the previous section (c)
, Ni, Ti, Zr, V, T&, Cr, PbSMo, W
, Co and other transition metals, and at least one selected from organometallic compounds and organometallic complexes. Siloxane compound.

(f) Polysilane represented by the following formula In the above formula, R5-R6 are hydrogen, an alkyl group of C1 or less, a haloalkyl group of C4 or less, a phenyl group %C5 to
C, is a cycloalkyl group, pencil group or vinyl group; n=l.

~10000.

Furthermore, the present invention provides a method for producing a carbon material, which comprises forming a mixture of a semi-inorganic polymer compound and raw coke powder into a molded body, and then sintering the mixture at 700 to 3,000°C in a non-oxidizing atmosphere. do.

The raw coke used in the present invention is a coke with volatile content that is produced at a relatively low temperature of 600°C or less, and may be petroleum-based, coal-based, or resin-based, but it is especially suitable for obtaining high-strength products. It is preferable to have a residual volatile content of 4% by weight or more. However, if the residual volatile content is too large, cracks will occur during firing, so the content is preferably 4 to 20% by weight.

Since most of the semi-inorganic polymer compounds used in the present invention are soluble in organic solvents, uniform dispersion can be achieved simply by mixing or kneading in a solvent. It has the advantage of easily contributing to strength and oxidation resistance.

Further, the semi-inorganic polymer compound used in the present invention may be linear, cyclic, ladder-shaped, cage-shaped, three-dimensional, or mesh-shaped.

The proportion of the semi-inorganic polymer compound in the mixture of the semi-inorganic polymer compound and the raw coke powder is 5 to 60%.
, preferably 10 to 50% by weight. If the amount is less than 5 ffl, it is difficult to achieve the desired oxidation resistance;
If it exceeds % by weight, it becomes difficult to exhibit excellent properties as a carbon material.

The semi-inorganic polymer compound can be directly mixed with raw coke powder, but in order to form a particularly uniform mixture, wet mixing or wet kneading using a solvent is preferably employed.

The solvent to be used can be appropriately selected from those capable of dissolving the semi-inorganic polymer compound, such as tetrahydro7rane, benzene, toluene, xylene, hexane, petroleum ether, dimethylformamide, and the like. In general,
Preferably, the mixing is carried out under heating.

Further, the use of a mixture of a semi-inorganic polymer compound and raw coke after calcination does not require consideration for cracks and cracks during sintering, and can be conveniently used. In order to obtain a preferable calcined product, the semi-inorganic polymer compound is heated at 30% in a non-oxidizing atmosphere, such as in a vacuum or a nitrogen gas atmosphere.
Sintering into carbon material is performed at 0 to 1500°C, preferably at 400 to 800°C, at 800 to 300°C in a non-oxidizing atmosphere such as a vacuum or nitrogen gas atmosphere
It is carried out at 0°C, preferably 1000-2800°C.

The sintering method may be any of the commonly employed normal pressure, atmospheric pressure, hot press, HIP method, etc., and can be selected as appropriate.

The carbon material of the present invention is a general carbon material in air at 800°C.
The oxidation loss is about 65-85% by weight in 1 hour and 1% by weight in 2 hours, but it is only 3% by weight or less in 10 hours at 1200°C.

Furthermore, does the carbon material of the present invention have a carbon material property?
In addition to t&temperature strength, thermal shock resistance, high thermal conductivity, good electrical conductivity, and low thermal expansion, it exhibits excellent effects such as high strength and oxidation resistance under high temperature conditions. Therefore, it is useful as a material for various equipment parts, a material for the ceramic industry, a corrosion-resistant material for the chemical industry, and a material for electrical and electronic parts.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 2.51 g of xylene and 400 B of metallic sodium were placed in an S L three-ring flask, and 1000 g of dimethylnochlorosilane was added dropwise little by little under an argon gas flow. After the completion of the dropwise addition, the mixture was heated under reflux for 8 hours in an argon gas flow. A precipitate formed. This precipitate was filtered, washed with methanol, and then with water to obtain polysilane as a white powder. Put 200g of this polysilane in an autoclave and
The reaction was carried out at 0°C for 15 hours. After the reaction is complete, dissolve it in n-hexane, remove it from the autoclave, filter it, and obtain a viscous solid semi-inorganic polymer compound (polycarbosilane).
120g was obtained.

To a solution of 30 g of this viscous solid semi-inorganic polymer compound dissolved in 100 mf of toluene, 110 g of raw petroleum coke (volatization rate: about 14% by weight) produced at about 500°C was added and mixed using a wet ball mill using a silicon carbide ball. After doing this for 5 hours, toluene was removed under reduced pressure to obtain a powder in which coke powder and semi-inorganic polymer compound were uniformly mixed. After crushing and classifying the obtained mixed powder, 2 t/
The molded body was sintered at 2100°C for 1 hour in an argon gas atmosphere.The bulk density of the sintered body was 1.95 g/cm', and the bending strength was 12.3 kg/llm2. The obtained sintered body was cut into a size of 10 x 10 x 7 + sm, and placed in an electric furnace preheated to 1200°C (in the atmosphere).
After heat treatment for 0 hours, the sample was taken out and the oxidation loss was measured.

The oxidation loss was 1.6% by weight, indicating excellent oxidation resistance.

Example 2 100g of polysilane obtained in Example 1 and 25g of polymethylsiloxane were placed in an autoclave and reacted at 470''C for 15 hours.9 After the reaction, the mixture was dissolved in n-hexane, taken out from the autoclave, and stirred. A viscous solid semi-inorganic compound was obtained.

50 g of this viscous solid semi-inorganic compound and 50 g of raw pitch coke made at 91°C at about 500°C (volatile content about 8% by weight)
) was mixed in a nitrogen atmosphere for 5 hours to obtain a uniform mixture of coke powder and semi-inorganic polymer compound. This material was calcined to 550° C. in an argon atmosphere. After crushing and classifying this calcined material, 2 runs cm
It was molded at a pressure of 2. By firing this molded body at 2100°C for 1 hour in an argon atmosphere, the bulk density was 2.2 H/am, and the bending strength was 15.2 kg.
/ ■ A sintered body of 2 was obtained. When the oxidation loss was measured by the same method as in Example 1, it was 0.7% by weight, indicating excellent oxidation resistance.

Example 3 300g of boric acid and 1500g of diphenyldichlorosilane
was placed in a 101-sized three-ring flask with 31 parts of n-butyl ether and allowed to react at 100°C for 18 hours with stirring to obtain a white precipitate after cooling. After distilling off n-butyl ether, the product was washed with water and unreacted boric acid was removed to obtain 121 sg of a borodiphenylsiloxane compound.

70 g of this boronophenylsiloxane and 60 g of the raw coke used in Example 1. Thereafter, a sintered body was obtained in exactly the same manner as in Example 2.

The bulk density of this sintered body is 2, l'g/Cm', +
The barge strength was 14, 8 kg/m2.

In addition, the oxidation loss measured in the same manner as in Example 1 was 1.2
The weight was 1%.

Example 4 200g of the borodiphenylsiloxane compound obtained in Example 3 and 20I of hydroquinone. were mixed uniformly in a 500 m flask, heated at a heating rate of 50°C for 1 hour in a nitrogen atmosphere with stirring, and reacted at 300°C for 1 hour to form a pale yellow semi-inorganic polymer compound. I got it.

35 g of this semi-inorganic polymer compound was dissolved in tetrahydro 7 run, and 8 g of the raw pitch coke powder used in Example 2 was dissolved.
5Fl was added, and while thoroughly mixing with a pestle, the tetrahydro 7ran was removed by evaporation to obtain a homogeneous mixture of coke powder and semi-inorganic polymer compound. Calcinate the calcined product until
After classification, it was molded at a pressure of 3t/am2. This molded body was fired at 1200°C for 3 hours in an argon atmosphere, and the bulk was reduced to v! J degree 1.98g/e Soko, bending strength 10
A sintered body weighing 3 kg/am' was obtained. The oxidation loss determined under the same conditions as in Example 1 at 1200°C for 10 hours was 2.9% by weight.

Example 5 30 g of aluminum isopropoxide was added to 200 g of the borodiphenylsiloxane compound obtained in Example 3, and the mixture was reacted at 350° C. for 1 hour in a non-oxidizing atmosphere to obtain a semi-inorganic polymer compound.

60 g of this semi-inorganic polymer compound and 9 g of raw petroleum coke (volatile content: 18) were placed in a 500 m 1, 4-necked, 7-glass tube, 200 j of xylene was added, and the mixture was refluxed for 3 hours with stirring in a nitrogen atmosphere. After xylene was then distilled off, the temperature was raised to 350° C. and stirred for 3 hours. The resulting mixture was thoroughly ground using a quarry, and then molded at a pressure of 3 t/am'. Next, this molded body was fired at 1500° C. in an argon atmosphere. The obtained sintered body has a bulk density of 1, 958/c163, and a bending strength of 14.
, 3 kg/mm2.The oxidation loss at 1200°C and 110 hours was 1.2% by weight.

Example 6 Anhydrous xylene 31 and 380 g of metallic sodium were placed in a 101 Mitsuro 7 flask, heated to the boiling point of xylene under a nitrogen atmosphere, and 540 g of chlorodichlorosilane was added.
and 800 g of 7-fluorochlorosilane.
The mixture was dripped at a rate of 0°31/hour from dripping a-). After completion of the dropwise addition, heating was continued for 20 hours. After the reaction was completed, the precipitate was filtered and washed first with methanol and then with water to obtain a white powder of polymethylphenyldilanph '1OFK.

A sintered body was obtained in exactly the same manner as in Example 1, except that it was dissolved in polymethylphenylsilane 00-1 and raw pitchcoke (approx. 10% by weight) was used. Bulk density of sintered body, 1
．． 98g/cs3, bending strength 9.8k! ? /ms
The oxidation loss at +21200°C for 10 hours was 2.6% by weight.

Claims (1)

[Claims] 1. A high-strength, oxidation-resistant carbon material made of a sintered body of a mixture of a semi-inorganic polymer compound and raw coke powder. 2. The carbon material according to claim 1, wherein the semi-inorganic polymer compound is converted into the following ceramic by heating at 700 to 2000°C in a non-oxidizing atmosphere; A ceramic mainly composed of SiC, which is either α-type, β-type, or a mixed phase of these. 3. The ratio of raw coke powder in the mixture is 40 to 9.
5% by weight of the carbon material according to claim 1. 4. The semi-inorganic polymer compound has the following (a) to (f)
The carbon material according to claim 1, which is at least one selected from the group of. (a) Polycarbosilane represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the formula, R_1 to R_5 each independently represent hydrogen, C_4
The following alkyl groups, haloalkyl groups of C_4 or less, phenyl groups, cycloalkyl groups of C_5 to C_6, benzyl groups or vinyl groups; n is 10 to 10,000. (b) Polycarbosiloxane represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the formula, R_1 to R_7 each independently represent hydrogen, C_4
The following alkyl groups, haloalkyl groups of C_4 or less, phenyl groups, cycloalkyl groups of C_5 to C_6, benzyl groups or vinyl groups; n is 10 to 10,000; and the repetition of x units and y units is random, Contains either or both blocks. (c) Borosiloxane compound represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the formula, R_1 to R_3 are each independently hydrogen, C_4
The following alkyl groups, haloalkyl groups of C_4 or less, phenyl groups, cycloalkyl groups of C_5 to C_6, verzyl groups, or vinyl groups; n is 1 to 10,000; and the repetition of a units and b units is random, Contains either or both blocks. (d) The borosiloxane compound of the preceding paragraph (c) and one or more organic compounds selected from aliphatic polyhydric alcohols, aromatic alcohols, phenols, or aromatic carboxylic acids, which are incompatible with the reaction. A modified borosiloxane compound obtained by reaction in an active atmosphere at a temperature within the range of 250 to 450°C, optionally in the presence of a catalyst. (e) Al for the borosiloxane compound in the previous section (c)
, Ni, Ti, Zr, V, Ta, Cr, Pb, Mo, W
Modified borosiloxane obtained by adding, mixing or combining at least one selected from organometallic compounds and organometallic complexes of Co and other transition metals and heating to 250 to 450°C in a non-oxidizing atmosphere. Compound. (f) Polysilane represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the above formula, R_1 to R_5 are each hydrogen, an alkyl group of C_4 or less, a haloalkyl group of C_4 or less, a phenyl group, a cyclo of C_5-C_6 It is an alkyl group, a benzyl group or a vinyl group; n=10 to 10,000. 5. A mixture of a semi-inorganic polymer compound and raw coke powder is made into a molded body, and then heated in a non-oxidizing atmosphere to 700~
A method for producing a high-strength, oxidation-resistant carbon material comprising sintering at 3000°C. 6. The ratio of raw coke powder in the mixture is 40 to 9.
The method for producing a carbon material according to claim 5, wherein the carbon material content is 5%.